Aspects of the present invention relate to providing access to broadband communication systems. In particular, certain embodiments relate to an apparatus which provides an interface to connect to broadband synchronous optical networks in order to provide a variety of synchronous and packet network connections.
In the past, a variety of transmission technologies have been used to electronically transfer large amounts of digital information, including both terrestrial and satellite links. Terrestrial facilities that have commonly been used include both buried and above-ground cable, microwave radio and most recently, optical fiber, which offers the largest bandwidth. Networks used for such high capacity data transport systems are typically synchronous networks.
In a synchronous network, data is transmitted from one location to another as a continuous stream of digital information moving from the source to the destination at a constant rate. The stream is organized as a sequence of frames, each frame containing a fixed number of fields in a defined order, each field of the same length. The Synchronous Optical Network (SONET) and Synchronous Digital Hierarchy (SDH) are the principal synchronous optical network standards currently in use. Because no single user normally needs all of the capacity of an optical fiber-based transmission system, the standards have been designed to provide a means to share the bandwidth.
The use of packet networks is growing in popularity due to the flexibility offered by the ability of a packet network to efficiently handle multiple data streams of widely varying bandwidth. Packet networks consist of a mesh of nodes interconnected by links, and data is exchanged in bursts called packets. Packets may contain voice, data, or video information, and can be of varying length. Each of the services supported on a packet network has its own set of requirements including, for example, end-to-end delay, packet loss, and privacy.
Synchronous optical networks are the primary transport mechanism for long distance transmission of information, and are becoming increasingly important in metropolitan areas. At the same time, the use of packet networks is growing rapidly due to their ability to efficiently carry multiple data streams of widely varying bandwidth. The number and variety of data services, the number of users, and the total bandwidth required at any particular user location will grow with time. Some legacy equipment requires lower speed synchronous time-division-multiplexed (TDM) network connections, while other equipment requires a packet network interface. As user demand for higher bandwidth connections grows and synchronous optical networks expand, support for connections of varying bandwidth will become increasingly important. Consequently, there is an increasing need for cost-effective and efficient means of interfacing synchronous optical networks and packet networks.
The functionality that may be needed to connect a SONET or SDH synchronous optical network and a packet network includes that of an Add-Drop Multiplexer (ADM) or terminal, a Digital Cross-Connect (DCC), and a Multi-Service Provisioning Platform (MSPP). ADMs may be used to transport SONET or SDH traffic on network ring topologies. The ADMs are nodes on such rings that are used to arbitrate (add or drop) traffic to or from the ring. A SONET/SDH terminal performs a function similar to that of an ADM except that the network connection is not in a ring configuration. A terminal terminates a high-speed point-to-point SONET path, and hands off a number of lower rate lines and paths on the client side. A DCC is a circuit switch used to switch and groom traffic between different lines and paths. A network may include several ADMs and terminals to arbitrate or terminate traffic along rings or point-to-point connections, and a DCC will be used to switch the traffic between all the paths. A Multi-Service Provisioning Platform combines the functionality of the DCC, the ADM, and the terminal along with the ability to support data protocols such as Ethernet to the client users.
Consequently, there is a need for a compact and cost-effective means of interconnecting synchronous optical networks and Ethernet packet networks. In addition, it would be advantageous to allow services supported using existing synchronous time division multiplex communication facilities to be supported over synchronous optical networks, in particular, metropolitan area networks. Therefore, a flexible, cost-effective, and efficient solution to the network interconnect problem is of importance.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.